Mana Prism

Tap it for one colorless, every turn, no strings: that first ability is the honest accelerant, the floor every later mana rock would be measured against. The second ability is where the price tag of an older game becomes legible. Producing colored mana costs an extra generic per activation, so the conversion is a net-zero wash on quantity: you spend one to get one back, shifting only which color you hold. This is a fixer that charges you for the privilege of fixing, and that premium is exactly what dates it. The intended job was to convert surplus colorless into whatever color a multicolor deck happened to be short, a far sharper problem in an era when fixing lands were scarce and painful to play. The shapes that followed (the various filter lands, the cheaper any-color rocks) attacked the same problem with less friction, which is why this particular design never made it out of its decade. What survives is the documentation: proof that "smooths your colors" was once considered worth a three-mana artifact plus a mana surcharge on every use, before Wizards decided color access should be cheaper and more abundant. Reading the second ability now is reading the rate sheet of a younger game, one that had not yet decided fixing should be close to free.